Yes this is common in inexperienced sheep particularly some breeds it seems. I don't have experience of Suffolks myself but I have certainly seen this with first-time Swaledales and Texels. You've done the right thing, pen her with the lamb and go in and support the lamb to get a feed. She'll get used to it very quickly and you'll soon find the lamb isn't hungry when you go in to help it. If the ewe is a bit udder-shy the lamb will quickly learn to pop in the back door when mum is busy eating.
With some sheep you do have to watch for baby-battering. I lost a really nice lamb to a Swaledale shearling a few years back; she literally beat it to death when we weren't watching - and having penned them so well, the poor mite had nowhere to escape. After that I have always tried, where the ewe shows any aggression at all, to pen them in a pen where there is a ledge or something that the lamb can use to get away from the ewe if necessary. Very occasionally a ewe is still too aggressive to risk leaving, in which case I don't leave the lamb with her unattended until I am sure the situation is safe. Oh, and that lambicidal Swaley got given a big strong orphan lamb who was plenty big and strong enough to take care of himself. After a week she gave in and became his devoted slave - and she knew her job the next year.
I'm sure your Suffolk won't be lambicidal - but I thought I'd better share that story as a cautionary tale just in case!
Oh, and I suppose I should have said, with any udder-shy ewe, it's worth just checking that there's nothing wrong down there making it sore for her when the lamb sucks. Sometimes it's just that the lamb is too greedy for her milk supply and is tugging and pulling at an empty teat.