[Waxing_Gibbous (Peter)]

I wouldn't recommend a 4SE for anything other than casual stargazing.
The mount (and other 'SE' mounts) are 'alt-az' or up-down, round and round mounts and not suited for astrophotography without a wedge.
Furthermore the 4-6" Celestrons (in my experience) are nothing to write home about optically and their small aperture and largish central obstruction (CO) give somewhat flat views with little contrast and poor definition.

IMHO, an 8" Newtonian on something like an HEQ5 or CGEM would cover both visual and AP almost perfectly.
This rig should come-in, at or, under budget (various coma-correctors and focal reducers aside) and give you a great start.

A short focal-length 80-100mm refractor would do just as well for wide-field but be less capable for Lunar/Planetary/DSOs and be a lttle more expensive.