do i need air vents in the roof

yes you do need an air flow this isnt expensive to do though so dont panic you just need some vented soffit putting on and in some cases some of your ridge tiles need changing to vented ridges usually every couple of meters also you my need some fascia vents in your dormas fascia every meter hope this helps

Yes you require cross flow ventilation which means , air can pass in through the eaves/gutter level and under the roof felt up the roof and across the ridge beam and then back down the other side , an air gap of 50mm should be kept between the foil backed insulation and the roof felt . The gap at eaves level can be acheivedwith a soffit strip or round vent grills ....Hope this makes sense Mark emmpire construction

All the information you require is in your building regs