Redhill has several areas - the centre, Earlswood - about 3/4 miles south of centre with own station on mainline and mostly Victorian/30s houses, Meadvale, which is to south of Reigate and Merstham, to north of Redhill, also with own station on mainline.
You do need to visit and drive round areas. The centre has the main chain stores of a town like where smiths and m and s. It isn’t cool or trendy and Reigate 2 miles away has the cafe culture and boutique shops and more expensive houses but not got the good rail connection.
Cheapest bits of Redhill are south Earlswood beyond the hospital and nearer Salford’s station rather than Earlswood. You’d get a 3 bed terrace for 350,000 there, or on the estate in Merstham.
Check out the areas and also schools. For primary, St Johns (between Meadvale and Earlswood) and Earlswood and Merstham Primary are fairly sought after. Lime tree is a new primary. For secondary kids go to Warwick (least sought after) or Reigate School if they live in the right bit of a Earlswood or Meadvale, or St Bedes (most sought after) from anywhere in Reigate or Redhill or villages if you have a 3 year record of regular Church attendance.
There are nicer and less nice bits. There is lots of countryside and nice parks in the town or nearby. Redhill isn’t a twee market town but lots of people are very happy there and huge numbers commute with journeys of about 30 mins from Redhill and perhaps 40mins from Earlswood or Merstham.
You’d need to visit. Go to the town centre (quite run down and wide range of people present there) and Memorial Park and Earlswood lakes/common and mercer’s Lake to get a feel.