Another option is to approach
Holts auctioneers and ask them to value the gun. Squinting at your pictures, a
starting price for what you have there is somewhere around £10,000 ($12,500), but it is very difficult to tell without knowing more.
As to the ammunition, first you need to know the calibre of the rifle. You can determine this either from the serial number (ie. the manufacturer ought to know) or by taking it to a gunsmith. Warning: certain old rifles have been rebored from their originally manufactured calibre and hence have a new, different, calibre.
Kynoch will be able to supply ammunition. You will shortly discover that it is not cheap to feed these rifles.
You seem to know how to take the rifle apart and put it back together. Is the rifle tight on face? (ie. can you move the barrels by shaking them while holding the stock).That is a big no-no, but can be cured relatively inexpensively. It may be worth
getting the rifle re-proofed, which again is relatively inexpensive and any competent gunsmith ought to be able to arrange. (It is important to do this via a competent gunsmith and seek his advice beforehand because proofing a rifle is a destructive process.)
At this stage, consider having the rifle thoroughly cleaned by a competent gunsmith - which will involve stripping it down and getting rid of any grease or dirt before putting it all back together. This differs from restoring it, which means reblacking the metalwork and oiling up the woodwork. You run the risk of devaluing the rifle by ill-advised restoration, and I suspect most people on this forum will advise against it.
Your profile does not say where you live. I can advise a number of British gunsmiths, but anywhere outside the UK is a closed book to me.
Of course, the whole point of having a rifle like this is to use it. Africa awaits!
