I moved from Highbury to St Albans 26 years ago!
London Colney has a catholic primary school, and there is also St Adrians RC, on the edge of St Albans.
Bricket Wood is a bit isolated, it is an odd infill triangle beside the M1, lots of parents try to get their children into Killigrew JMI in Chiswell Green, and secondary can be problematic, unless your child is bright and can take the exam for Parmiters and Watford Grammar. There is St Michaels RC secondary, but I don't know anything about it. People end up with Francis Coombe which is not one of he best.
London Colney has changed a lot, there are not really any bad areas there, some of my nicest clients live there and have a lovely middle terrace house with good size garden. There is a good community spirit, and they still have a library! Plenty of parks, splash pool, tennis court and lovely walks. I don't know what sort of budget you are looking at, but would be happy to send you a local paper.
London Colney for secondary would be the new Samuel Ryder Academy which is going to be 3-18 years, but traditionally as LOndon Colney is the "inner" of the "outer: area, children also go to STAGS Loreto and Verulam. In Colney Heatt there is Nicolas Breakspeare, an RC secondary. I live on the outer of the inner area, neither LC or St A and ended up having to go privately as we didn't get any schools! The drive to the station is 7 minutes or 20 min brisk walk!
I have raised 2 children here, run NCT, been a school governor of 6 schools, from nursery to secondary,( still am) so happy to answer any questions.