Lord Ashcroft has released a big "marginals poll". This is slightly different to the usual style of these: he selected 26 constituencies and polled over 1000 in each, so there are results for each constituency, and if you want to look at overall figures the sample size is unusually large. Whether the sampling is any good I don't know.
The overall result gives a 6.5% swing from Con to Lab, much better for Labour than the recent ComRes marginals poll. Some of the details look a bit weird, and the wisdom of doing this in the middle of an EU election might be questioned; there are some very high UKIP scores, although he doesn't have them in the lead anywhere.
Amber Valley: Lab 41 (+4) Con 29 (-10) UKIP 20 (+18) LD 6 (-8)
Broxtowe: Lab 42 (+4) Con 31 (-8) UKIP 14 (+12) LD 8 (-9)
Gogledd Caerdydd: Lab 41 (+4) Con 34 (-3) LD 8 (-10) UKIP 8 (+6) Plaid 7 (+4)
Hendon: Lab 41 (-1) Con 38 (-4) UKIP 13 (+11) LD 5 (-7)
Great Yarmouth: Con 32 (-11) Lab 31 (-2) UKIP 29 (+24) LD 5 (-9)
Lancaster & Fleetwood: Lab 45 (+10) Con 28 (-8) UKIP 12 (+10) LD 7 (-12)
Morecambe & Lunesdale: Lab 39 (-1) Con 36 (-6) UKIP 16 (+12) LD 7 (-6)
North Warwickshire: Lab 39 (-1) Con 33 (-7) UKIP 19 (+16) LD 5 (-7)
Sherwood: Lab 41 (+2) Con 29 (-10) UKIP 21 (+18) LD 5 (-10)
Stockton South: Lab 44 (+6) Con 34 (-5) UKIP 14 (+11) LD 6 (-9)
South Thanet: Con 31 (-17) Lab 31 (nc) UKIP 26 (+20) LD 8 (-7)
Thurrock: Lab 36 (-1) UKIP 31 (+24) Con 24 (-13) LD 5 (-6)
Waveney: Lab 38 (-1) Con 31 (-9) UKIP 21 (+16) LD 6 (-7)
Wolverhampton SW: Lab 46 (+7) Con 31 (-10) UKIP 15 (+11) LD 4 (-12)
Bolton W: Lab 41 (+2) Con 30 (-8) UKIP 19 (+15) LD 6 (-11)
Brum Edgbaston: Lab 41 (nc) Con 33 (-5) UKIP 15 (+13) LD 6 (-9)
Derby N: Lab 41 (+8) Con 26 (-6) UKIP 20 (+18) LD 8 (-20)
Dudley N: Lab 39 (nc) UKIP 29 (+21) Con 25 (-12) LD 4 (-7)
Halifax: Lab 41 (+4) Con 27 (-7) UKIP 19 (+17) LD 8 (-11)
Hampstead & Kilburn: Lab 42 (+9) Con 33 (nc) LD 15 (-16) UKIP 4 (+3)
Great Grimsby: Lab 37 (+4) UKIP 25 (+19) Con 23 (-8) LD 9 (-13)
Morley & Outwood: Lab 39 (+1) Con 27 (-8) UKIP 22 (+19) LD 6 (-11)
Southampton Itchen: Lab 35 (-2) Con 27 (-9) UKIP 25 (+21) LD 10 (-11)
Telford: Lab 38 (-1) Con 28 (-8) UKIP 25 (+19) LD 4 (-11)
Walsall N: Lab 37 (nc) UKIP 32 (+27) Con 22 (-12) LD 5 (-8)
Wirral S: Lab 43 (+2) Con 30 (-9) UKIP 15 (+12) LD 6 (-11)
http://lordashcroftpolls.com/2014/05/conservative-labour-battleground/