It does depend on the circumstances, have these been explained?
Was the property unregistered (if so the Land Registry will not have the deeds and proof of title will come from the individual title documents)? Have all reasonable attempts been made to trace them rather than just relying on an indemnity policy?
Indemnity polices are not nessarily the coverall that people think they are and have become increasingly common these days in legal practice.
If you are getting a mortgage then it is likely the lender will need to approve the policy and certain conditions on the policy are likely to need to be fulfilled or the policy may not be enforceable. These can be before and after cover is put in place and likely to include certain efforts being made to trace missing deeds, possible statutory declarations and such. There may also be restrictions on things you can and can't do after the purchase such as certain parties you cannot approach.
I would ask to see a copy of the policy and have the terms of it explained to you including to cover limit and circumstances in which it can be used and what the any payout can actually be used for.
Think of the circumstances which could cause problems later on such as an "unknown" missing deed turning up proving that the property has not been validly transferred and someone else claiming that they legally own the property.
Or similarly a situation in which it does not appear that you own the full extent of the land you thought you purchased or there are onerous restrictions or problems which you are unaware of. Find out how any policy would be able to be used (or not) in such circumstances.