i live in surbiton. Lots of the links people have posted are either not in Surbiton at all, or not in the centre, which misses the point. Living in central surbiton (where your original property is) is just great. Instant access to all the shops, coffee shops, train, river, Victoria rec, etc etc. even being a 10-15 min walk away (let alone the 20+ of some of the links) just isn’t the same.
we bought a flat in Surbiton last year (prioritising location over it being a house). No kids yet (I’m pregnant) but we absolutely love it. Given how full of buggies central Surb is on a Saturday morning, I think other people must have made the same choice too!! I think the original flat looks very very nice, light and spacious and airy, makes such a difference.
so yeah I would go for that type of property in your position and wouldn’t compromise location for garden if deep down, you don’t want to. Most people who live in central surb do live in flats and there will always be a demand for flats there I think because of the commuting links.
plus maple infants and SASM are very very good schools unlike some others in the borough