YouGov have polled 10,000 people:

The final ComRes poll:

And Survation:

FINAL @dailymirror poll. Headline is ballot paper. Sample size 4088:
CON 31.4% LAB 31.4% UKIP 15.7% LD 9.6% GRE 4.8 SNP 4.7% PC 0.4 AP 1.9%

— Survation. (@Survation) May 6, 2015

The Tories need a better result than that…