Need help cleaning my computer and improving performance

I’m looking for a tech-savvy helper to clean up my computer and boost performance. The computer runs slowly, has unnecessary programs, and plenty of temporary files taking up space. I’d like a thorough cleanup, including removing junk files, updating software, running a malware scan, and organizing files. Preferences: perform a clean restart afterward, back up important data if needed, and provide tips to keep it running smoothly. I’m available around mid-morning; please propose a start time that fits into a 2–4 hour session. UK-based service preferred. Basic English is fine, but clear explanations are appreciated.