It's hard to express what I want to say because I don't want to be rude or indelicate.

'I've had a look and it will take some time, I did not expect these documents to be so long! To be honest I thought I could do it quickly this evening, however it will take longer than what I expected and I won't have the time to finish it until the end of the week. Is it ok for you? What's your budget for this project?/Is there a budget for this?'

Change "than what I expected" to "than I expected" (than what = noooo!) and personally I think that's an excellent reply.

Maybe "I was expecting it to be something I could do quickly this evening" rather than "to be honest etc" - you don't have to make excuses, just state facts.

Sounds great to me - just take out the "what" between "than" and "I"

You're right 'than what' is awful, I'm exhausted hence this unforgivable mistake ('ce à quoi je m'attendais' in French).

'I've had a look and it will take some time, I did not expect these documents to be so long! I thought I could do it quickly this evening, however it will take longer than I expected and I probably won't have the time to finish it until the end of the week. Is it ok for you and is there a budget for this?'

I removed the 'to be honest' which was a bit too much.

Nitpicky I know but I would keep it as you did first time, have 'Is this OK for you?' as one sentence and 'Is there a budget for this?' as a separate sentence. More effective I think.
Go for it, and I really hope you get the job if it's what you want.

Thank EuroTrash, I just sent it.

We'll see what will happen but I think it is wrong to work for free if it's not just a 'sample' to show how you work.

Depending on the urgency, I could do 20 pages of solid text (each of 30 lines, = 300 words) in a day, if pushed. I refused once, and that particular work went to an English confrère in the UK, and I lost an otherwise good client...
On the other hand it would probably take me a day to translate 10 lines of literary text, AND it would sound like a translation!
@Babyposer
My two daughters have the same problem, in the other direction. They were born and bred in France and, although theoretically bilingual, still make mistakes in English sometimes, esp. ever since they left home.

If they prefer to have a degree-qualified translator then I can give you a contact. UK guy who was at school in Paris but mother tongue is English.
Degree from Durham university. Currently doing freelance translating.

100% bilingual is almost impossible I guess! I'm still learning new words in French and English and this will probably last my whole life.

I'm still learning both (esp. modern expressions in English - I'm still using slang used in the 60s)

No reply yet. Don't know what to think.. we'll see

Somedoby told me a few days ago that a "woman who does" is a "cleaning lady". Never heard it before and I'm still sceptical

Let's not talk about "a woman who doesn't" then!

Thats slang for wife

It might be a generational thing, but I as a Senior would say "Ethel does for me on Tuesdays" (if she did so).