I am going to go down the route of "Wait until you are 18 and buy a RIF not a 2-tone".
How often do you think you will able to go to a skirmish?
I don't mean that in a patronising way but say you site charges £15 gun rental (quite cheap for rental), most guns that are worth buying are around the £150-200 mark, so you would need to skirmish AT LEAST 10 time with the gun before it is has been a economical option. That is 5 skirmishes a year, which for me with my own job and car is fine but for yourself (who I assume will be going to 6th form in September) money is tight and time is a factor too, you will have exams that will take up 2 months of the summer and a month of the winter and you will have course work and home work to do.
My opinion is you wait until 18 (and if you have been skirmishing on an off during the 2 years membership isn't a problem) and you can buy yourself a lovely metal and wood AK (which are beautiful guns) without having to have lime green covering half of it (a sin unto all that is holy). In those 2 years you can have a go with other guns (I recommend G3's if you like Ak's) and save up for more than a budget starter gun, which will be well worth it trust me on this.
2-tones reduce the credible reason for us to be allowed to use RIF's, unless you have the money and the time to go AT LEAST once a month there isn't that much point in buying you own gun now. Plus you will end up spending an extra £100 on a vest and mags and batteries too. DO some research and take your time, there is no point rushing thing just because you enjoyed it once, go to more skirmishes and if in 2 years you are still dead set on airsoft then invest in a good gun, you wouldn't believe the difference in feel and reliability.
I am not trying to put you off only to give you the value of my experience, we were all young and living at 100mph once, but not everything works best at those speeds.