With regards to HOP - when we bought over 3 years ago the 3 beds on Whatman Road were in excess of £400k so I think if you're looking for a victorian property in HOP you will be out of luck. I wouldn't bother putting letters through these doors, it would also be a waste of your time and money as they probably wouldn't market them for less than £450/500k.
We bought our 4 bed for £430k (in need of a lot of work) and probably would market it for around £600/£650k now based on recent sales.

I remember looking at 3 bed 30s around Cibber and Colfe and they were around £350k so you might find something round there but it would be a "project". You wouldn't get a finished article for less than £400k.

You should be able to get a flat/maisonette... not sure if that's an option, there are a number of victorian maisonettes in HOP which should be in this price bracket...

As a previous poster suggested you might be better off looking further down the overground. It won't be HOP or FH, but things are bound to improve in all areas over time - and you're more likely to get a seat on the overground further south!!

If you really want a house in HOP or FH, you will probably need to up your budget and potentially look at something non-victorian. There are some houses on Garthorne Rd that might be in this price bracket? You could also look at the Catford borders - 20 minute walk to FH station though.

Bottom line - feel free to leaflet I'm sure no one will mind, but do some research so that you target houses where you really feel they should be <£400k or it will be a waste of time and money.

Good luck and I hope you get the house you want soon!