Right first off, do what’s right for you - not what’s going to make your children “close”. Big age gaps aside, being close in age will not make them close - personality and gender will be far more important here.
This is the most useful post on here really. I had my first at 40, and knew that if I wanted more than one, which I did desperately, then I would have to try and have two close together.
Once I'd had my daughter though I was knocked for six, physically (c section) and mentally, and just couldn't even start contemplating ttc again for at least two years (and she was a ridiculously easy baby and toddler who slept v well). Sadly we've lost two pregnancies this year, and she is almost three, so at the minimum there would be almost a four year gap. I don't worry too much about them being close in age, but I do now feel a certain reluctance to go back to nappies and sleepless nights.
So basically, there is no ideal time, no ideal age gap, and life doesn't always work out how you plan it anyway. If you feel up to it then go for it whenever you want (the free nursery hours are a bonus, if you can time having no. 2 when no. 1 qualifies, but the whole system may have changed again by then anyway).
There are 16 years between my brother and I, and he is just the best big brother anyone could ever ask for, whereas my friend and her brother (two years apart) haven't spoken to each other for ten years. The two year age gap always seems a bit mad to me when you consider having to get them through A levels and GCSEs in the same year!