i dont think its the best to be honest, unless you have a new lex you wont have isofix, mine is 2001 and i dont, there are very few car seats that fit in the seats properly, they all have what they call buckle crunch which is unsafe. i have a recaro seat which seems ok but there is still slight buckle crunch. Def get s seat protector, especially if you have leather.
as for the boot, i hope you have a small pram, we had a mamas n papas multi one and it was honestly like the krypton factor trying to get it in, took ages every time. now we the lil one is older and we have a lil buggy its fine, but before it was terrible, all shopping had to go on back seats