Initially you could phone Silverline 0800 4 70 80 90 just for a chat. I think they can arrange regular chats with the same person if you need that. Or if you wish to talk about concerns or problems try Samaritans or Mind.
I know what it's like to feel as you do. The present situation makes it harder to make the first steps towards meeting in groups in your area of course. You could use the time to do a lot of research though about what's going on [U3A, WI etc. Try the library too to see what's happening [walking groups, keep fit, book clubs etc.] near you. Also online penfriends.
I too am struggling a bit today, I am very active in the WI and we had just started to have a few garden meet ups, six at a time. I was looking forward to going to two next week except I live in Greater Manchester and we are now facing new lockdown restrictions - no mingling in gardens! So it's back to staying at home. We have used Zoom a lot recently but numbers are tailing off as folks are starting to go on holiday or visit family. It feels worse for me as my WI is actually in a local village two miles away which is in Cheshire with no lockdown.
I was due to visit my mum at her care home today ( in a gazebo in the garden) but they have two positive Covid 19 cases so went into total lockdown again yesterday.
Ah well, we in the NW have our one day of the heatwave so I'm going to sit in the garden and crochet!
I was feeling that way early this morning . Lonely and negative about the future - I felt bad . But I gave myself a kick , took myself out to cut the hedges and an absent landlord of the house next door appeared to cut hers too , so we had a lovely catchy up session . Then my window cleaners appeared , 3 lively lads who told me all about their holidays that they're looking forward to next year ! So maybe that's the secret , get outside , see what other people are doing , someone might appear needing a blether too !