What motivation might working class people in england have had to sign a contract to work to work as an indentured servant?

I assume we talk about Aristocratic Victorian England. The reality of that time is that working in great estates (said to be 'in service') was seen as quite a respectable job. Much more respectable than a farmer. People generally got food, water, accommodation and wages as well.

Choices? im thinking spain but with no choices its a bit vague