Indeed you should buy an electric gun. This is a UK based forum, so any retailers that we mention should ship to you as well. Have a look in the 'Places to Buy' subforum and post a thread there asking about a retailer if you can't find one on them already.
The best retailer for a gun on a budget is Zero-One, as they will 2tone your gun for free if needed. Other good UK based retailers include Proairsoftsupplies, firesupport and Land warrior airsoft.
If you are over 18 and decide to go to 3 games in no less than 2 months, you can have your details put onto the UKARA database which will give you a personal code known as a UKARA number or defence. This can be used to buy realistic (IE black, tan, olive drab, dark coloured etc.) guns, otherwise known as Realistic Imitation Firearms or RIFs.