Yes, you’ll need a piano on which to practice in between lessons. Keyboards look similar to pianos but are actually very different. Keyboard keys have a smaller  depth and they’re not weighted. For these reasons, practising piano on a keyboard can actually be detrimental to your technique. Also, keyboards usually have 61 keys whereas pianos have 88 keys. This can be very confusing for a beginner, and often, by grade 1, you will be playing pieces which have a range larger than 61 keys meaning that they will be unplayable on a keyboard. There are many bargains you can acquire on Facebook Marketplace. Some of my students have purchased fantastic, nearly new digital pianos with weighted keys from there and paid under £100! However, please avoid any acoustic piano listings which are ‘free’ of charge. Often these pianos are old with worn strings and cannot be tuned up to concert pitch (e.g. if you play a C on a flute, it matches the pitch of a C played on a piano). If you do decide to purchase a digital piano, ensure you purchase one with weighted keys. Acoustic pianos are built with weighted keys and manufacturers of digital pianos create the same effect for digital pianos. ‘Graded Hammer Action’ is also something you could look out for (although not essential) meaning that the higher keys are lighter to press than the lower keys, again reflecting the action on an acoustic piano.