I just got an almighty GOOD quote off bell.co.uk, ive not lied or ought but you'd think i did to get it that cheep. . anyway, do they HAVE to honour it or can they get out of it and say they wont do it so cheep?

basically I got a quote as a 2nd driver on my car my dad being the first driver for £367 tpft

just wondering if im gonna get fobbed off if i try and go ahead with it?