How do I know what awning will fit my caravan

Could someone offer some advice please. We are newbies who will be picking up our caravan on the 15th May ( excited!). Having driven past our local campsite and seen pictures of campsites when looking for sites to stay at this year, it seems that near enough everyone has an awning. Thus, we have concluded they are a vital extra to have!?? I have posted on the parts, accessories, awning etc section but have had no reply to date, so trying here. So, sorry if this sounds a silly question but are all awnings a generic fitting so not caravan model specific? can anyone offer me some advice on getting the right one for a Buccaneer Schooser? I have read the spec for a Schooner and it states 10,900 mm. Any advice on awnings in general most welcome. Thank you