Old property is what I thrive on,
Crumbling bricks can be cut out and replaced depending on the extent of the damage it may be best to strip and rebuilding using your existing materials. However I'm guessing that your property will have a listing status so it would be very wise to contact the local authority as your first port of call before a tool is lifted! This way it will save time, heartache and your finances in the long run.
The local authority will then direct you towards the apporate hertitage body for you I.e English heritage I'm guessing?
Check out there website there is an abundance of technical knowledge on there and it's in plan English no builder talk! And it's free.
Best of luck