The website is www.justyou.co.uk.

The contact page gives some clues:
Just You
Compass House
Rockingham Road
Market Harborough
Leicestershire
LE16 7QD

Telephone numbers:
To request a brochure: 0870 252 8008
To book: 0870 252 8080
Customer Services: 0870 252 8111
Press Office (Journalists Only): 01858 410 018

Fax numbers:
To request a brochure: 01858 461 956
To book: 01858 461 956
Customer Services: 01858 434 323
Press Office: 01858 432 202
Operations: 01858 466 477

A search for TRAVELSPHERE on 192.com gives 01858 410818 and 01858 410456.

A search of the database on this site gives 01858 468400, you may have to ask for reservations, as well as the two quoted above from 192.com.