that should be ok
a lot of sparks apparenly just put them in the meter box
might be an idea to ask your rec if they are ok with this
also iirc you should have your own overcurrent protection as well as isolation
and finally while you may be allowed to use tails i personally dislike the idea of runnign unprotected conductors of that capacity for any significant distance
contactum do a 2 way metalclad CU with a 100A isolator
http://www.tlc-direct.co.uk/Products/CMM2N.html and a 100A 2 module wide mcb (
http://www.tlc-direct.co.uk/Products/CMDK401.html)
you will want to remove the busbar and neutral bar link and wire the mcb direct to the rcd with single or tail but its a practical cheap and resetable option