Turn the question around on the agent...
Feed them a line about not wanting to price yourself out of the market, but don't want to sell yourself short and not be taken seriously, afterall they're usually on a percentage, so when you earn more, they earn more. Explain that you understand the market conditions are tough so you're trying to get a feel for what market rates are? Push your luck and ask what sort of range other candidates are being put forward at...
'lowest rate' always sets alarm bells off with me. Does the agent (or rather client) want good or cheap. Everyone wants value, but best value isn't always cheapest...
If Employers NI is new to you, be aware that you'll be required (and well advised from an IR35 perspective) to seek insurance also. I use Caunce O'Hara for this.
Consider PCG Plus membership if you'll be outside IR35, and don't scrimp on the accountant either. There are all sorts of areas where you can save money and get things cheaper, but then we get back to the 'value' aspect.
I'm happy to pay a little more than I could pay elsewhere for the excellent service I get from SJD Accountancy. I don't want to have to chase my accountant for the sake of £20 a month...
Setting up a limited company might be better saved for when you're certain that contracting is for you, but I prefer this to working with an umbrella company. Chasing a third party that doesn't seem to understand that their responsibility is to turn contracts and payments around in double quick time gets tedious quickly.
Technet Plus is worthwhile for the software and licenses you get as well, keeping sharp with the latest kit in a VM environment is worth consideration.
Be prepared to travel (including staying away during the week) if you want more money. Familiarise yourself with the vetting procedure before applying for security cleared roles, but be aware that if you can get sponsorship, then cleared roles usually attract a premium.
Rough breakdown
~£2400pa in PAYE/Employee NI/Employer NI (based on a ~£11k salary)
~£1200pa to the accountant
~£250pa for PCG Plus
~£250pa for Technet Plus
~£300pa for Insurance
The figures above are slightly inflated because a; it's always a good idea to budget for more than things will actually cost for a bit of contingency, and b; because I'm lazy and can't be bothered to go looking for the exact figures.
Either way, budget £4k-£4.5kk pa and remember that you'll have unpaid leave (bank holiday, holiday and sick) and periods out of work to contend with when you're calculating day rates versus salary etc...
The flip side is that the rates should be higher, and IR35 plus the flat rate VAT scheme should bolster your overall earnings if you're good/flexible/lucky...
Good luck...
