Solid wood worktop - butt joints - correct sealer/glue?

Just about to start a DIY project to install new solid wood worktops with my Dad.

I need to make two butt joints. I'll be using biscuits and bolts. The instructions for the worktops say I should apply an end grain sealer or Cascamite glue to the joint surfaces, plus a thin bead of silicone sealer. I can't find Cascamite in my local B&Q so what should I buy as an end grain sealant? Is there a specific product or should I use a varnish of some sort? Or would standard PVA wood glue be suitable?

Next question: I'm trying to find a natural cure low-modulus silicone sealer as recommended by the worktop instructions. None of the no-brand or Unibond silicone sealants in B&Q mentions whether they have these properties - they just say vague things like 'flexible'. Would these retail sealants be suitable or do I need to get something specific from Screwfix? http://www.screwfix.com/prods/42697/

Sili - Cascamite is now called Polymite and is available in small 125g tubs up to 6kg buckets.

Thanks Symptoms. It seems Polymite/Cascamite/Extramite are now all the same thing. Just need to find some now...

Sili - You can get it from www.axminster.co.uk or Toolstation do a type called Resintite