There are other posts on this site with information. It may well be worth doing a search to get a better range of responses.
Getting into teaching is hard. It's difficult to get the qualification without experience and you don't get the experience with the qualification...
A teacher ultimately needs to get the DTTLS qualification. A lead into this qual is the PTTLS qual. You could do this to give you an idea of teaching, its demands and so on, but the PTTLS qual is expensive and takes about 3 hours a week in a class for 10 weeks, and then at least that in homework each week, if not more.
If you did the PTTLS course (I believe the Guild do them online, or you could do it at your local FE college), and then wrote to your local FE college, they might give you once class to teach each week and you could build up that way.
A word of warning - don't even think about taking on too much at the start. You will probably spend about five hours preparing for every hour of teaching you do at the start.
Alternatively, you could write to your local FE college and say you were thinking of teaching and do they need a classroom assistant for a half day each week? This would be unpaid, but a great way to get in the door.
Something that does work, and that isn't very often tried, is to turn up to an information day or open event at the local college and talk to the staff.
You will probably find you get no response at first. Staff in FE are so busy they just don't have time to deal with the sheer numbers of queries that come in. Keep trying and your name will stick in their mind, but don't badger them or you'll be written off.
Good luck.