Wherever there is space I think, put up a poster, maybe think of trying the big supermarkets as well? (The big Sainsburys is a good idea, I can't remember where the adds are placed now, as they are doing the store up but ask at customer services) They have small places where you can post adds, so that will reach a few people, Pets At Home also have an area like this. There is woodland further round from the travelodge (go down past the cinema and gym, keep going down a little pathway, past the childrens nursery? and it leads out towards woodland) so maybe check around there. That road that you meet up with going towards the woods leads on to a residential area so definetly poster around there. If you follow that roads down, on the right is a large garden centre called Bybrook Barn and they have a place to put adverts too, so you could put a little add there. Next door to that is the doctors and they may let you post an add there, I am not sure.
If he has gone the other way out of the travelodge then there is a road to cross, then into woodland and fields which soon turn into a golf course, I am not sure where the reception of that is situated but if you google map it, they may let you place a poster in their reception?
There is a public footpath that leads all around the golf course so it is possible to walk through, although it would be a long walk and would depend on Grapelli's attitude towards roads (would he go away from or towards?)
There are a few vets in ashford, they will let you place posters in a 'lost' folder, Barrow Hill is the closest vets to where he went walkabouts, but theres also Kingsnorth vets, Peter Edgar vets and the companion care vets in Pets at Home, is he microchipped?
Oh and opposite the travelodge is a garden centre, Dobbies, have you placed an add in there or wandered around in there? the plant area outside is massive and they have chickens, so might be worth a wander?
I really hope you find him soon! I will keep an eye out, sorry I can't be much more help, but I am at work all this weekend