I think the only university that does Met as an actual degree is Reading. It's therefore quite competetive and you'd need something like ABC at A level, or maybe higher.
Met at university level is not so much focussed on the practical but more on the theoretical. LOTS and LOTS and LOTS of mathematical models that would blow the average mind.
Unless you're very mathematically minded and can use computers to - like - advanced programming level in something like C and Perl, you might want to think twice about doing a Met degree.
If you're not like that, but still want to study Met at uni, then do a degree that will allow you to study a few Meteorology/Climatology modules. Like Environmental Science, Geology with Geography, Geography BSc etc.
Or, just study something that will keep you captivated for 3 years. Or maybe do a degree course that includes the 14 ATPL exams (for which you will have to pay in full, I think).