mylittlemonkey - you have hit the nail on the head so to speak!
alice - it sounds like you are missing your "old" life and maybe resent your partner for having his old life still? If you don't resent him, apologies - I know I resent my dh at times!
Someone made a valid point - make sure you get some exercise, if your gp is happy for you to. Even just walking in fresh air helps.
I have enjoyed meeting some new mums, but much prefer meeting up with my "old" friends who knew me pre-baby, I meet them and forget I am a mum but am "me". So could you meet up with some friends and ask your partner or someone else to look after the baby?
I know it is early days for you with a newborn, but you will get there. At 5 weeks, a baby doesn't do much, but as they get older and more interactive so to speak it will get better. My dd is 8.5 months and a joy to be with mostly!
Also, if you miss work, you can do KIT days if you and your employer agree. I have done a few and it has really helped me - use my brain, remember I'm me and can do my job, and earn some ££s in the process!
Sorry to ramble in the reply, hope this helps! good luck.