Probably best you discuss a flock health plan with your vet - they will know the local area and climate and the most likely problems you will face.
The lambs will definitely need vaccinating - if you use heptavac, that sounds ideal, they will need two injections as recommended on the packet, I believe from 3 weeks of age, but check that too.
They may need worming depending on conditions, there is a worm called Nematodirus that can kill lambs before they show signs of scour or show up on faecal egg tests, but this is very dependant on local conditions, so speak to your vet who should know what wormers would be effective and if there is likely to be a problem.
Can I ask why the ewes all had Alamycin? This is an antibiotic, and should only be used for specific conditions, under the advice of a vet, so as to prevent bacteria developing resistance to antibiotics. It is not usually used as a blanket treatment. If your vet advised treating all the ewes, there would be a specific reason, and this may influence what you do from here.
Best bet is to have a chat with your vet, mostly advice is free, and can get it tailored to your situation.