This guide refers more to family tents for SUMMER holidays and generally tunnel type tents

Tunnel Tents : Supports bend round to form a tunnel.My knowledge is based on learning the hard way.

There are generally many types a few things you should consider.

1. Rain Proof, the rating is based in mm and it refers to the amount of water in height the cover can take befer leaking. for example 1000mm means 1m of water can sit on the tent before leaking. However this is based on testing only of the material. In reallity rain falls and heavy rain means it can produce pressures locally on the tent at these levels. Never get a tent with a rating below 2000mm and if you want to have a chance of staying dry Id recommend at least 3000mm.. Ours is 3000mm and only had my drips from outer flysheet once during very heavy rain.

2. Construction/ErectionCheck how the tent is erected. tunnel tents as others usually have an outer fly sheet which forms the main water proofing. Inner tents can hang from this main outer tent which means the outer sheet is put up first (great for putting up in wet weather) or there is a seperate inner tent which has to be put up first.The iner tent made from breathable, partly water proofed material. Birth plan  for comfort 3man compartments usually best to sleep two adults.

3. Inner Tents. It is best and far more comfortable to have an inner tent with sewn in groundsheet. This gives full isolation from the wether. many tents have flysheet with inner sections for bedrooms, but a groundsheet has to be placed on the floor ~(only flysheet betweeen you and the elements). On plans look for extension of inner lines (usually dotted or red) too see extent of inner tent/compartments.

you can get a very good 2000mm with grounsheet and inner sections for bedroom >6 birth for <£100. which will give you a very good experience. A 3000mm with seperate inner tent sewn in groundsheet will be usually >£200.