That's a pig of a journey. I used to commute from Burgess Hill to Guildford. M25 was virtually always slow moving at the time I wanted to travel and the A281 was slow with virtually no overtaking opportunities. Assume you have had an interview but have you tried driving the two routes at rush...
Can you not strike a deal with a local B & B for Tues/Wed/ Thur nights. Might give you worthwhile rates if they know it's going to be over a long period? Where abouts is the destination?