Hi,
From what you've said so far, the siuation sounds quite sh*t. I work in Glasgow and the company I work for has a contract with a company you may work for. I've been the customer on the end of the tight SLA's so can understand the expectations that are set on your behalf.
I work tier 2/3 in a similar support environment and between work and a long commute I had to re-adjust work/life . I am moving to a new job soon with better pay, working hours and a company that values life outside of work (i hope).
Your wage is extremely poor for the job/level you have described and has obviously not been benchmarked in 10+ years.
I would brush up your C.V. I've used Lee at The CV Store[/url]a few times in the past and have never failed to get an interview. There are plenty of jobs in Glasgow for your field, but you may need to adjust the roles you are looking for, especially to reduce stress. Look for jobs working directly for a company onsite rather than a support provider. You will be valued more and don't have the stress of worrying about expectations as much.
I know a lot of people in the Glasgow area who I can ask to keep a look out. Not recruitment agents, but staff working in established companies who have strong IT teams.
My email is in my profile. Give me a shout if you want to chat about it of even meet up for a pint in the town to talk anything through.