These are some of the locations in 'The Annals of Fear', as exact as I could find them on Google Streetview. If you're never used this before, then just click on the image. Then use the arrow keys on your keyboard to virtually travel along the streets.
The New Forest
Unfortunately Mello and Matt's house in the New Forest is fictitious. However, I've put you on a road in the area. Let me know if you find a real life house matching their house.
Gorskica
Once again a fictitious place. I was going to choose a random small town near to Krapina, on the basis that Gorskica is bound to have been similiar. I was thwarted by the fact that Google Streetview haven't made it up into those mountains yet. Here's a map of the 'hood instead.
Mullhyttan
Mullhyttan is a real place! Yes! *happy dances* Unfortunately, it's not been photographed by Google Streetview. Here's another map.
Cambrian Mountains
The Manor that they stay in is fictitious. So you're got a random backroad over the Cambrian Mountains instead.
Machynlleth
Finally, somewhere that is both real and been visited by Google Streetview. Here is Machynlleth, where Century is collected from the station. I've parked you outside the Parliament Building.
Aberystwyth
Deontic and Century shop there; Century ends up in hospital there; then most of the gang stay overnight in a disused barracks there. I've left you in a random street in the heart of the town.
Winchester
Wammy's House is got to be around here somewhere. However, I've left you at the Cathedral.