well,I don't think there is much chance of being rejected from universities next year:
1) you have 3/5 offers at top 10 unis
2) pooled for Cambridge
However, this is assuming you get AAA at A2... at least.
On the other hand, a year is a long time, and you would be expected to read a lot more about philosophy for Cambridge interview. Traveling is bound to be one of the best experiences you could possibly have but working for it will take time and effort. Also, most of your friends might go to university, which can be quite lonely.