No - bailiffs cannot enter a property if there is nobody at home unless they have gained 'peaceful entry' the first time round. i.e if you let them in once, they may be able to break in on subsequent vists.
If bailiffs turn up, make sure all doors and windows are locked and speak to them through the letterbox or an upstairs window. They are allowed to enter through open doors or windows
They are not allowed to take goods belonging to anyone else although how you would prove who owns them I'm not sure. The first time bailiffs come in, they should do a 'walking possession order' where they basically make a list of all the goods and the value. They will then leave the goods where they are and make an arrangement with you for repayment of the debt. If this is not adhered to, they can return and remove the goods listed previously.
Lots of helpful info can be found here:
http://www.insolvencyhelpline.co.uk/debt_basic s/bailiff-guide.php