does anyone know where i can get rid of 4 gas bottles.

You can take them to the tip.

Scrap man may give you metal price for them too.

If they are the larger type of gas bottles (like the Calor Gas bottles for BBQ's) you should take them back to wherever you bought them as, chances are, you probably paid a deposit on them in the first place.

You might also find the following info of use:-

http://www.calor.co.uk/customer-services/faqs/general-cylinder-queries/

you can take them to the calor gas place by Cammell Lairds