Have you just read the survey? If you haven't already, then arrange a phone meeting with the surveyor... They should be happy to talk to you and are often more frank /open than what they will write in the survey.
It might be something of nothing or it might be cause to negotiate the house price depending on how competitively priced the house is.
This really and it depends on the score tbh think anything below 0.9 is seen as acceptable
Was it down as a C2 or C3?
Any outside pics? Check bottom rows of bricks for spalling
If there is any and it stops below the Damp Proofing level then that's indicative that the DP is doing its job really (might eventually need the bricks replaced tho.
Surveys annoy me, we'll take your money to tell you "might need looking into" haha
From the link above..
AVERAGE COST OF TREATING RISING DAMP:
Depending on the complexity of the job, it usually takes: 2-5 days
£2750
Then
The cost of repairing rising damp can vary wildly.
Then
For the easiest possible situation with minimal damage, it could cost as little as
£400 to fix all the problems and the damage. If the issue has been left unchecked and causes extensive damage, you could be looking at as much as
£16,000.
So yet again a completely pointless "estimate"
you know where the house is, go speak to the vendor and let them see the survey and your concern?