With zero small aircraft cockpit time, at the very minimum go and do a five hours starter pack somewhere (cost £600 - £800). You will be spending a lot of time in the enviroment, so find out if you like it. One trial flying lesson, is not enough...that's just a thrill trip. You need to find out what it is to learn in light aircraft.
If you kind afford a starter pack, you cannot afford flying lessons...period.
If you go a decent flying school, your starter pack will include an introduction to all the possible routes to a flying career.
If you find out that you like it, and you can afford it, the very next thing is the medical (which will cover eysight).