I'm very new to astronomy and got myself a cheap, used 700mm 70mm diameter refractor scope and am able to see (what I think are) good images of the moon. However when I try to view planets I see nothing but a very small dot! Pretty sure I was looking at Mars this eve (slight red colour) but with a 10mm lens its still just a dot. I can make out no detail. Same with Jupiter. Should I be able to see detail with the specs I have? Thanks in advance.
Most likely you will not see much detail except that they are a really tiny disc and don't wobble like stars.
The moon has an apparent diameter of 30' (half a degree) in the sky. Mars' apparent diameter varies between 3.5" and 25" (so about between 1/1000° and 1/120°). Thus at closest approach Mars is still about 60x smaller than the moon, currently at ~<10", it's about 1/180 compared to the Moon). How much detail do you see at such tiny fraction of the Moon in your telescope?
You can expect to see on Mars maybe some very slight colour variation between equator and poles. On Jupiter with an apparent diameter of ~50" (thus twice Mars' apparent size) you might see some slight colour changes with the cloud bands in its atmosphere and on Saturn you might see that it has rings.
All the images with details on the surface are both, taken with a camera and selected for (missing) atmospheric distortion and post-processed to enhance the features, and taken with a larger telescope where you can use a larger magnification.
But even with a larger telescope (longer focal length AND larger apperture), you WILL need to have good seeing; there are nights where even with a clear sky, also a larger telescope will not resolve features due to the seeing, thus the influence of Earth's atmospheric disturbances.
At the moment (January 2021) Mars is the only planet that you can easily find. Venus, Jupiter and Saturn are all too close to the sun. The diameter of Mars is currently about 8", so about 1/250th the size of the moon. Even at the best of times, such as last summer, Mars is a small object, and small telescopes will not show much detail.
In 6 months time, Jupiter and Saturn will be easily visible in the late evening sky. They will both be much bigger than dots. Saturn is spectacular because of its rings.
Jupiter is bigger and has the attraction of its 4 Galilean moons. Surface detail is clearly visble but the markings are quite subtle. Don't expect to see anything like the images you see on-line or in magazines. The great red spot is not as great, nor as red as it used to be, and can be quite difficult in a small telescope - but sometimes it pops out and is unmissable.
For all the planets (and other astronomical objects), it pays to practice viewing, as you get to be able to see more detail. Don't give up!