Just to tell you my experience and knowledge after all these years in the industry.
1) You NEED CompTIA A+ for basics of technology
2) Network + is the next level to show you know the way networking works, BUT is best done hand in hand with SECURITY + which is paramount to showing you understand much more than 'this is a web browser' and 'that is a NIC'.
3) CCNA is the main certifications to get you Cisco trained, and most demanded to demonstrate you know how to do the entire network infrastructure especially GLOBALLY, which means outside of the office your in there to some office in another location (India for example).
4) Your in the UK, one of the PRIMARY demands over there is ITIL, I would go get the ITIL V3 Foundation after you get CompTIA A+ as that is a Euro standard that without it will keep you from ever being interviewed.
5) PROBLEM: IT Industry is SATURATED and is DOWNSIZING RAPIDLY, as the 'tech' changes to make the IT 'guys and gals' obsolete. The only 'growth' segments in IT field isn't "supporting" IT like you posting about, but in MANAGING IT, which is mainly your CCNAs, SQL Programmers and Software/App programmers. These are the ONLY GROWTH field (especially if you take MEDICAL FIELD specific Programming course work, which is a HUGE growth industry).
So in all and all I would NOT suggest trying to 'get into' the job field as your query is lined up at present, there is TOO MANY already out there, and almost all Windows based company systems are 'outsourced' for support from much cheaper regions that can 'remote' to the systems and do the work for 1/20th the cost of Euro/American workers. Just got through interviewing for a position with a company that is recovering from FIRING 550 IT employees, and MASS outsourcing the work to India. India remote packages updates, manages the accounts, fixes the email, does the servers, etc. What they needed was a SINGLE employee in person to actually 'replace the mouse' or 'turn ON the computer' for someone on vacation. See not what you thinking, and this was A typical of all the Corps internationally.