London Starter Pack

A few of my friends who moved to London/UK asked my advice regarding a few common topics so I've compiled the list of things I've told them and I'm putting it here for anyone else who may find it helpful.

Housing
I've always shared flats in London so these websites may be better suited for people renting a room:
Spareroom.co.uk: my favourite one, offers are filtered and it has a great search engine / alert system. Early bird option is worth the cost as it may help you secure a great deal.
Gumtree.com: Lots of offers but be careful with deals too good to be true. Some are fakes to lure you in to get in touch with an agent who will try to offer you something else (generally more expensive).
Moveflat.co.uk: Not as many offers as the above ones but not bad.

Regarding British tenancy laws, your landlord has to put your deposit in a Deposit Security Scheme (DSS), make sure you ask him for the DSS details.

Final advice: if you see a flat/room in London that you like and the price is good take it immediately. If you don't chances are someone else will. It's a very competitive market.

Foreign Exchange
Transferring money home, or to the UK, using conventional banks may become very expensive as their rates and fees are not amazing. You get better deals using specialised Foreign Exchange providers. I've only used one and I've been very happy with all the transactions I've placed through them.
SmartCurrencyExchange.com: You call them and get a quote for the amount of money you want to transfer (I've got rates as good as 2% above spot price). Transfer pounds to their pound bank account and they will transfer euros the destination account you wish in 3 business days. They also support other currencies.
ATM Machine / Debit Card: I've written about this here (in Portuguese), the summary is you get charged fees for every transaction. If you are doing many (6 or more) it's better to withdrawn as much money as possible as opposed of several small card transfers.

Taxes and National Insurance
The best website to get information about this is HMRC. Some companies will help you get a National Insurance Number, while in other cases you'll have to take care of it yourself.
IRS: For people whose only source of income is their salary they don't need to fill IRS forms. Taxes will be deducted from your salary and HMRC will repay you some tax back if you started working half way through the fiscal year or if you leave London before the fiscal year ends.
You got a Per Annum offer but now you are wondering how much you'll get in the end of the month after taxes? Check listentotaxman.com. BTW, contrary to certain continental countries, in the UK you'll only get 12 salaries per year. There are no extra subsidies for Xmas or holidays month.

Getting Around London
Don't forget to buy an Oyster Card once you get to an Underground Station.
tfl.gov.uk: TFL handles Buses and Underground and they have a great journey planner on their website
Barclays (Boris) Bikes: For £45/year it's a great way of travelling in London!

Getting out of London
By plane, check skyscanner.net to find the best flight rates, don't forget to chose "London All" as this will find flights to/from all airports around London.
By train: NationalRail.co.uk
By bus: MegaBus.com, low cost buses, NationalExpress.co.uk, normal coaches service

Health
UK has the reputation of having one of the best Health systems in the world. It's called NHS and you can use their website to find out all you need to know.

Communications
Calling home from your mobile phone/landline can be expensive. There a few other cheaper methods:
Skype.com: obviously you can use Skype to make calls using the internet but you can also use it to call to phone numbers (rates)
Voipcheap.com: A cheaper way to call phone numbers from the web is Voipcheap, not only the rates are better thank Skype's it also offer freedays to call landlines for free. If you have a slow internet connection you can also call a Voipcheap's local phone number from your phone and then dial the number you want to call using your voipcheap credit.
WhatsApp/Viber: have a smartphone with an internet connection? Chances are you are already using one of these apps. They are great to keep in touch with folks back home either by sending messages of phone calls.

Living Costs
So you got a big offer to work in London, but how much does it actually cost to live in London?
Expatistan.com: Expatistan helps you compare the cost of living in your present city to the one you are moving.

Shopping
You got yourself a flat and now you need to buy some appliances, bed linen, gadgets, etc. Where to go?
argos.co.uk: There are many Argos in London and chances are there is one close to you. There will find very good prices on a very wide range of products. You can oder what you want to buy from the website, go to one of the shops, pay and collect.
amazon.co.uk: With free delivery on so many items it's hard not like Amazon. Probably the best website for electronic products, media and books.
ebay.co.uk: Most renown for its auctions ebay also lets you buy from shops, including shops in China that will sell you incredibly cheap adapters and gadgets. After you search for something click on the "Buy Now" tab and this will show you item for available for sale.

Enjoy your stay in London and have fun!