You can't go wrong with core subjects. However they aren't a walk in the park. Depends on what you enjoy, go on your college website and check out there courses, they give quite a detailed description of the course aswell.
- English Lit
(I assume your doing 3 not 4?)
First of all, you really shouldn't worry about your age gap. 19 is far from old and colleges cater for students of all ages anyway. I bet no one will even know how old you are unless you tell them. As for which A-levels to do, none are easy, so the best advice is just to choose the ones you'll enjoy most so you'll be more motivated to work hard at them. Which subjects did you enjoy most and do best in at GCSE? If you know which course you want to do at uni, check the entry requirements to see what A-levels you need, if any.
I think you should go for it regardless of age. My sisters in the same position as you and she's 21.
However, you may have to be with adult learners as the sixth form centre usually takes 16-19.
You say you're good at IT, why not do IT A-Level? Although you said it bores you, so maybe not..
Regarding the age, don’t worry about it. You’re still young at 19 and have your whole life ahead of you. You shouldn’t worry about re-starting and going off to do A-Levels. It’s vital, to make the best of it that you can, that you don’t go with this worried attitude. People really won’t care that you’re a bit older.
I’m in a similar situation myself, I’ll be starting at 18 although within a month or two of starting will be 19.
Regarding the subjects, the best you can do is choose subjects which you enjoy – or think you will enjoy – and not simply go for whichever are perceived as the easiest. You should also think about which subjects would be best for you to follow your chosen path afterwards (university/career).
Also, you’ll be older and more mature, and while it may seem a pain to still be in education at 19 – and seeing as I’ll be in the same situation, I know exactly what you mean – you’ll realise later on in the future that you made the right choice and won’t care about having been two years behind, so to speak.