Blue Peter Books are poor sellers so not a huge amount.
A search of completed items "blue peter book" gives 1097 results of which 93 have sold so just under a 10% sell through rate.
The 1964 edition in excellent condition I would expect to get about £30, for any of the later ones your looking at £1/2 each at a push.
With a job lot may get someone who wants to just complete a collection in one go and may pay a slight premium for the convenience for getting all the books in one go.
Personally I would try them at £100 BIN with Best Offer and I'd probably take any offers over £70
