Thank you John.

I make my own sanding sealer with clear dope and talc or micro ballons.I thin the dope up to 50% and vary the fillers according to the grain etc i wish to seal.You can ajust the proportions to suit yourself. The greater the fillers to dope the easier to sand . I usually finish with an 800 grit. Experiment to find what suits you best.Discount store talc will do. Cheapest you can find .Baby talc is often the cheapest. Regards John

Thanks robbob I will take a look now.

Hi justintime2001.
Here's what I used:
http://www.ebay.co.uk/itm/500ML-Cellulose-Sanding-Sealer-Clear-Seal-Softwood-MDF-Hardwood-/181824180681?hash=item2a5590d1c9
I actually got the 1litre size and have used about half of it so 500ml may be sufficient for you.

Robbob.