No doubt that England are gonna miss KP, but I think given the seriousness of his injury he was never gonna last the whole series, Bell is no doubt a far inferior batsman than KP, but I won't just write him off as a joke batsman.
Yes, he had an awful time before being dropped from the English side last time around, but he is still a pretty decent batsman with a pretty solid technique, he would be really keen to revive his test career, and that determination might bring the best out of him, and he might contribute decently.
Though the other way to look at it is, he might get too nervous and uptight (like he has been before) and might just end up proving to be a walking wicket for us, or atleast that's what I'm hoping for.