make sure that you are clear / right about when you are to be paid ie ascertain with precision exactly when you should be or should have been paid
if then not paid on that day write a notice to the employer setting out his breach (ie non-payment) and stating that if not remedied within 7 days (say 3 or 5 or 7) you will understand him to be in repudiatory breach and to no longer require your services as employee
if still not remedied within that timetable in theory you should be free to walk without comeback
then sue his bottom for the outstanding fees (including loss of income for the period after you walked); this should not really require lawyers
I have no idea if an employment tribunal would deal with such claims - I suspect they may do in which case use since the whole process is designed not to require lawyers; ask the CAB for advice
you have to move quickly though ET time limits are v short
your post indicates that you are not in fact an employee
alternatively sue in the county court: issue proceedings (ie go to court and fill in a claim form and pay fee and serve on your employer)
on the claim form write down the claim pretty much as per your post but spelling out exactly what money he owes you and how calculated
add claim for interest (just say "I also claim interest: section 69)
as noted above when claiming you can include not just past loss but any future loss as a result of walking out ie the income you would have earned if you had stayed in the job if the reason you walked was his failure to pay / honour the agreement
just make sure it's all v clear, unemotional, accurate, precise, using ordinary language as per your post; leave out anything irrelevant and include all relevant
if it won't fit on to the claim form just write "see particulars of claim attached" on the form and write out the claim on a seperate piece of paper headed "particulars of claim"; ideally type but don't worry if can't
ask the court office for advice on the procedure and/or CAB or equiavlent
also consider approaching Bar Pro Bono Unit (google to find address) and ask them to take your case on
all info required should be on the internet somewhere ....
the only bit to worry about is "pre-action protocol" - you need to check if there is such a protocol relevant to your claim and if there is follow it
this involves writing a letter before action
etc
another bit to worry about is suing the right party: this will presumably be obvious from your contract
however in practice if the employer is some doomed start-up company it may be bust by the time you get to judgment and that may prevent you recovering any money anyway
bear in mind that the individual (who may be loaded) is not necessarily your employer if (as is normal) he trades through a limited company
if you sue the wrong party you will have a major problem so take care with this bit
once proceedings are underway you will have to do exactly what the court says exactly when they say
xxxx