Well, if you can't afford nuclear
you'll not be keen on the implications of other policies, even if we look only at capital cost:
EDF's current budget for the developments at Hinkley Point and Sizewell is £19Bn. That includes grid connections, etc. That's for 4 x 1600MW EPRs. A capital cost of (19/6.4) Bn/GW = £2.98Bn/GW. If we assume that those will run at similar capacity factors to Sizewell B (just over 90% averaged over life and including the recent extended shutdown for pressuriser repairs) - that'll be about £3.31Bn/GW average output.
A consortium of Dong Energy and Masdar is currently building the "London Array" windfarm. It's what's called "near offshore" - that is, in shallow water, close to the coast. It costs more than onshore, but much less than the far-offshore stuff that the German and UK wind development plans rely on. It's fairly representative of the sort of mix that we'll both use if the developments go ahead.
London Array is due to cost €1.9Bn for 635MW, exclusive of grid connections. At current exchange rates, that's £2.57Bn/GW - but, on current experience, it's likely to operate at about a 0.27 capacity factor (German offshore experience is slightly worse - that indicates something under 0.25). That's therefore £9.55Bn/GW of average output - or, 2.9 times the implicit capital cost of nuclear.
Your own experience in Germany with solar is even more salutory - in 2008, Germany had approximately 5.3GW of solar pv capacity installed. It operated at an average capacity factor of about 9% - so, and average output of 477MW. The capital cost of those installations is around €35Bn. That's about £64Bn/GW, or just under 20 times the implicit capital cost of nuclear.
Note, in both of those latter cases, if there's more than minor penetration into the grid, you obviously have to operate back-up plant, or storage to offset intermittency. Those numbers ignore that incremental cost.
If you want to look at storage costs, we've also some recent UK numbers to compare with. The only large volume energy storage system that's even close to economic viability is pumped-storage hydro (when I say "viable", it's obviously never going to compete directly with baseload power, since it has to buy baseload power to store - it relies on price differentials between low and high demand).
SSE is building two pumped storage plants along the "Great Glen". They'll cost about £1.2Bn/GW, and can store enough water for about about 5-7 days output (uselfully, about as long an interrval of low wind ouput as we tend to see in a single event) . Were you to use that technology for wind, to allow you to guarantee that you could maintain steady output, you'd need to add (based on that same capacity factor) about 300MW per GW of wind capacity. So, we'd add that onto the baseline cost of the wind system - to give an equivalent cost of about £14Bn/GW average output.
Doing the numbers for coal and gas is harder - their economics aren't dominated by capital costs, as are nuclear and renewables, so it's not really viable to do comparisons on capital costs only (on current finances, of the cost of a unit of nuclear-generated electricity, about 80% is capital and financing cost, about 90% for wind (excluding back-up), and about 95% for solar. for comparison, for non-carbon abated gas it's about 20%, and for non-abated coal about 30%; no-one yet really knows what's the cost and efficiency impact of Carbon capture, but it's sure as hell not cheap).